Automatic well casing filling apparatus



Sept. 13, 1955 BAKER 2,717,648

AUTOMATIC WELL CASING FILLING APPARATUS Filed June 25, 1952 2 Sheets-Sheet 1 C I t 1 I, .10

rToH/v R. BAKEQ,

IN VEN TOR.

ATTOQNEY.

Sept. 13, 1955 J. R. BAKER 2,717,648

AUTOMATIC WELL CASING FILLING APPARATUS INVENTOR.

BY W W ATTOQNEY.

United States Patent 0 AUTOMATIC WELL CASING FILLING APPARATUS John R. Baker, Pasadena, Calif., assignor to Baker Oil 'fIools, Inc., Los Angeles, Calif., a corporation of Callornia Application June 23, 1952, Serial No. 295,053 17 Claims. (Cl. 166225) The present invention relates to subsurface well apparatus, and more particularly to apparatus for automatically filling a string of well casing, or the like, with the fluid in the well bore as it is lowered therewithin.

An object of the present invention is to provide improved apparatus for enabling a string of well casing to automatically fill with the fluid in the well bore during lowering of the casing string in the latter.

Another object of the invention is to incorporate a back pressure valve in well casing,

of the casing in the well bore, will automatically fill with the well bore fluid, and in which improved means are provided for releasing the back pressure valve whenever desired, in order to allow it to engage its companion seat.

A further object of the invention is to provide an improved diflerential valve mechanism in a shoe or collar adapted to form part of a casing string, which enables the casing string to fill automatically with the well bore fluid during its descent therewithin, and in which the fluid internally of the casing string only rises to a predetermined level that is substantially lower than the fluid level externally of the casing string.

Yet another object of the invention is to provide an automatic valve control mechanism of the above noted character, that possesses a comparatively large passage area, to minimize the danger of foreign objects plugging the mechanism, and to decrease fluid erosion of its parts.

Still another object of the invention is to provide an automatic device for controllably filling a string of well casing with well fluid, and having a seal ring arrangement that is subjected to comparatively low friction forces, to minimize interference with movement of the device between open and closed positions.

Yet a further object of the invention is to provide an automatic device for controllably filling well casing that is of simple, strong and sturdy construction, and which is comparatively economical to manufacture.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

Figure 1 is a longitudinal section through an apparatus embodying the invention, disclosed attached to a casing section lowered in a well bore, the parts being arranged to allow the well bore fluid to flow into the casing;

Fig. 2 is a view similar to Fig. 1, with the lower valve mechanism closed;

Fig. 3 is a view similar to Figs. 1 and 2, in which the automatic filling portion of the apparatus has been renand prevent such I valve from engaging its companion seat during lowering in order that the casing well casing while it is being 2,717,648 Patented Sept. 13, 1955 2 dered ineffective, and the back pressure valve thereabove has been allowed to engage its seat;

Fig. 4 is a greatly enlarged longitudinal section of the apparatus in open position, and corresponding to the position disclosed in Fig. 1;

Fig. 5 is a cross-section taken along the line 55 on Fig. 4.

The apparatus A disclosed in the drawings actually forms part of a casing string B, or similar conduit string, that is to be lowered in a well bore C to a desired depth. The apparatus is illustrated in the form of a casing shoe secured to the lower end of an adjacent casing section B, but it is to be understood that the apparatus could also be constituted as a casing collar disposed at an upper or intermediate point in the casing string.

The apparatus A includes an outer tubular member 10 having an upper threaded box 11 for threaded attachment to the lower end of the adjacent casing section B, forming part of the casing string extending to the top of the well bore. This outer tubular member is provided with a plurality of longitudinally spaced internal grooves 12 to receive companion ribs 13 formed when a cementitious plug 14 is cast within the tubular member, in order to anchor the plug to the latter. The lower end 15 of the plug is usually rounded, to provide a guiding nose, for the purpose of guiding the casing string past obstructions or restrictions that might be encountered in the well bore C.

The cementitious plug 14 has a central passage 16 that may be considered as extending throughout its length. The upper portion of this passage is encompassed by a valve seat 17 cast into the plug and adapted to be engaged by a back pressure valve element 18, preferably in the form of a ball buoyant in cement slurry, to prevent upward flow of fluid into the well casing. For the purpose of insuring against leakage between the ball 18 and its companion seat 17, a suitable seal ring or annular seal element 19 is clamped between the seat 17 and a retainer ring 20, the retainer ring being urged against the seat by a tubular stop member 21 disposed within the cementitious plug 14. This stop member is provided with a plurality of circumferentially spaced lugs or fingers 22 against which the ball valve member 18 may rest when in a lower position disengaged from its companion seat 17.

The mechanism so far described is known, per se, and will function to allow downward passage of fluid through the casing string B, but will preclude return flow of fluid into the casing string whenever the ball valve member 18 is allowed to engage its valve seat 17. Initially it is desired to preclude such engagement for the purpose of allowing the fluid in the well bore C to automatically fill the well casing B during lowering of the latter within the bore hole to the desired landing depth.

The back pressure valve element 18 is prevented from engaging its seat 17 by a mechanism that allows the fluid to enter the casing string through the shoe A, and this mechanism may be hydraulically actuated to release the ball valve element when desired. Moreover, the mechanism for allowing the well casing to fill with fluid may be so designed and arranged to only allow the fluid to fill the well casing B to an elevation that is less than the fluid level externally of the well casing. It may be desirable to maintain the internal fluid level substantially less than the external fluid level; to provide some buoyancy in the lowered through the fluid in the well bore. In addition, the maintenance of the fluid level internally of the well casing B lower than that externally thereof may be of advantage in preventing the fluid from flowing over the upper end of the casing string, which oftentimes occurs during running the casing in a well bore. This flowing over drenches the equipment at the top of the hole, as well as the personnel, rendering the working conditions unsafe and uncomfortable. By maintaining the fluid level at a suflicient distance below the top of the well casing, overflowing is prevented, as well as the disadvantageous and unsafe conditions just noted.

The mechanism for controllably filling the well casing is disposed in the lower portion of the outer tubular member and the cementitious plug 14. Thus, an adapter ring 23 may be cast in the plug 1 bearing against the lower end of the stop member 21. This adapter ring is engaged by the upper end of a valve housing member 24 that has peripheral grooves 25 formed therein for cooperation with companion ribs 26 in the cementitious plug, to secure the valve housing member 24 to the plug 14 against movement in any direction. Such securing also serves to prevent longitudinal movement of the adapter ring 23 within the cementitious plug.

The upper portion of the housing 24 may have a cylin drical wall 27 along which a guide and retainer membe 28 may slide. This latter member has an upper spider portion 29 whose periphery may slide along the inner cylindrical wall 27 of the housing. The upper end of the spider 28 engages the lower end of the adapter ring 23, the parts being initially retained in this position by one or more frangible elements 39, in the form of one or more shear screws threaded through the upper portion of the housing 24 and into the spider. The spider has circumferentially spaced, longitudinally extending ports or openings 31 to allow fluid to pass therethrough in both directions.

The ball valve member 18 is initially prevented from engaging its seat 17 by being releasably attached to the spider 29. Such mode of attachment is obtained, as disclosed in the drawings, by threading the upper end of a tie rod 32 into the ball valve member 18, and piloting the lower portion of the tie rod into a bore 33 in the retainer and guide member 28, the tie rod being attached to the retainer member by a frangible connecting element 34, such as a shear screw, threaded transversely through the retainer member 28 and into the tie rod 32. When the shear screws 24 securing the spider 29 to the housing 24 are intact, the shear screw 34 attaching the tie rod 32 to the retainer member 28 serves to position the ball valve member 18 in engagement with the stop lugs or fingers 22, in which the ball valve member is disposed a substantial distance downwardly from its companion seat 17.

The cylindrical portion 27 of the housing 24 extends downwardly from the spider 29 to a substantial extent, terminating in a stop shoulder 35 which can be engaged by the lower end of the peripheral portion of the spider when the shear screws are disrupted, as explained hereinafter. Below its cylindriral portion, the housing has an inwardly extending flange portion that provides a cylindrical seat 37 having a substantially lesser diameter than the cylinder wall 27 thereabove. This seat is adapted to be engaged by a valve member 38 to prevent flow of fluid through the casing shoe A, or the valve member 38 may shift upwardly to an open position, to permit flow of fluid through the cylindrical seat 37 and upwardly through the shoe.

The valve member or head 38 is in the form of a movable cylinder, which is slidable along a guide rod or stem 39 integral with and depending from the spider portion 29 of the retainer member 28. The valve head 38 may occupy an upper position in engagement with a stop shoulder 40 at the lower end of the spider 29, in which an upper cylindrical sealing surface 41 on the periphery of the head is out of engagement from the cylindrical seat 37, to allow fluid to flow through longitudinal passages 42 in the head and through the seat. These passages 42 are formed between radially extending guide ribs 43 projecting from the inner portion 44 of the valve head to its cylindrical seat. When the valve head 38 moves downwardly, its cylindrical sealing surface 41 is disposed within the cylindrical seat 37 to prevent fluid from flowing through the shoe. This latter position is positively determined by engagement of a shoulder 45 on the valve head with a shoulder 46 formed on a cap 47 threaded onto the lower end of the guide rod or stem 39. The diameter of this cap 47 is greater than the diameter of the valve stem 39 thereabove, for a purpose that will be explained hereinbelow. In view of this greater diameter, the cylinder wall 48 of the valve member 33 has an internal diameter which is greater than the internal diameter of the cylinder wall 4-9 above the shoulder 45, which is slidable along the periphery of the guide rod 39. Accordingly, when the valve member 38 is an upward position, such as illustrated in Figs. 1 and 4, an annular cylinder space 50 is present between the guide rod 39 and the inner Wall 49 of the cylinder.

It is preferred that the well fluid be prevented from entering the above-noted cylinder space 56*. For that reason, suitable seals are provided between the guide rod 39 and movable cylinder head 33, and between the latter and the cap 47. As specifically disclosed, a rubber or rubberlilre seal ring 51, such as an O ring, is disposed in an internal groove 52 in the upper portion of the valve head 33 above the shoulder 45, and adapted for slidable sealing engagement upon the guide rod 39. Similarly, a rubber or rubber-like seal ring 53, such as an O ring, is disposed in an external groove 5 in the cap, for slidable sealing against the inner wall 43 of the cylinder. These seal rings 51, 53 effectively prevent the well fluid, or any other fluid, from entering the confined annular cylinder space 50.

As stated above, when the shear screws 30, 34 are intact,

the back pressure ball valve member 18 is held in a downward position disengaged from its seat 17. The shear screws 30 attaching the spider 29 to the housing 24, in eifect, cause the guide rod cap 47 to remain sta tionary. However, the valve head or movable cylinder member 38 can move longitudinally along the guide rod 39 and cap 47, and with respect to the cylindrical seat 37 between open and closed positions. During lowering of the casing string in the well bore, as illustrated in Figs. 1 and 4, the greater pressure externally of the casing string shifts the valve head 38 in an upward direction, in which its cylindrical seating surface 41 is out of engagement from the cylindrical seat 37. Accordingly, the well fluid can flow through the passages 42 between the ribs 43 and through the ports 31 in the spider, continuing on through the annular spaces between the lugs or fingers 22, around the ball valve member 18 and through the valve seat 17 and central passage 16 into the casing sections B thereabove. If the valve head 38 moves downwardly, in which its shoulder 45 engages the cap 47, then the cylindrical seating surface 41 is disposed snugly in engagement with the cylindrical seat 37 in the housing 24, and no further well fluid can pass upwardly into the well casing B, nor can well fluid pass downwardly from the well casing.

The valve member 38 moves to the downward position just mentioned when force acting downwardly on the upper portion of the valve member is greater than the force acting in an upward direction on the valve member.

it is preferred that the automatic filling device operate in such manner that the fluid level within the well casing B is maintained to a predetermined lower level than the hydrostatic head of fluid externally of the well casing. This result can be accomplished by properly proportioning the projected area of the valve head, over which the fluid therebelow is acting on it and tending to urge it in upward direction, with respect to the projected area of the valve head over which the fluid within the well casing is acting in a downward direction thereon.

As disclosed in the drawings, the projected annular area R of the valve head member 38 between its inner cyl ndrical wall 48 and the cylindrical sealing surface 37, which is the area over which the fluid therebelow is acting, is less than the annular area S between the guide rod 39 and the cylindrical sealing surface 41, and over which the fluid within the casing string is acting to urge the valve member 38 in a downward direction to closed position.

Abalanced condition will exist when the pressure on the valve member therebelow and acting over the area R is equal to the pressure within the well casing acting downwardly on the valve member over the area S. Expressed by way of formula, a balanced condition will exist on the valve member 38, neglecting friction, when P1R=P2S in which:

P1 is the external pressure or hydrostatic head of well fluid outside of the well casing B acting in an upward direction over the annular area R, and

P2 is the pressure of the fluid internally of the well casing, or hydrostatic head of fluid internally of the well casing, acting downwardly on the Valve head 38 over the area S. I

Inasmuch as the area S is greater than the area R, a lesser pressure or hydrostatic head within the casing string is required to shift the valve head 38 in a downward direction into sealing engagement with the cylindrical seat 37 than the hydrostatic head or pressure of the fluid externally of the well casing. If, for example, the area R is only ninety per cent of the area S, then the valve will close when the hydrostatic head of fluid within the well casing is slightly greater than ninety per cent of the hydrostatic head of fluid externally of the well casing.

In the operation of the device, the casing shoe A (or collar) is attached to a casing section B forming a portion of the casing string, and the latter is then lowered through the fluid in the well bore. During such lowering, when the hydrostatic head of fluid outside the well casing is too great compared to the internal hydrostatic head of well fluid, the valve head 38 is shifted to the upward position disclosed in Figs. 1 and 4, and fluid will then flow through the open valve device 38 and around the back pressure valve member 18 into the casing string B. As the fluid level increases internally of the casing string with respect to the external fluid level, to satisfy the above-noted equation, then the internal pressure will shift the valve head 38 downwardly into sealing engagement with the cylindrical seat 37, as disclosed in Fig. 2, closing the valve device and preventing any further fluid from entering the casing string. Of course, if the casing string B is then lowered to a further extent, the valve 38 will reopen to allow more fluid to enter the casing string, while maintaining the level of fluid internally of the latter less than the fluid level externally of the latter. Such opening and closing of the valve member will occur until the casing string has been lowered to the desired depth in the well bore.

When the desired depth in the well bore has been reached, the device for allowing the well casing to fill with well fluid is not needed to any further extent. However, the back pressure ball valve member 18 should be freed, to allow engagement with its seat 17. Accordingly, the casing string may be filled completely from the top of the well bore, and pressure applied on the fluid within it. The valve head member 38 occupies the lower position in engagement with its cylindrical seat 37; so that passage of fluid in a downward direction from the casing string is prevented. Accordingly, pressure can be built up in the fluid in the casing string acting in a downward direction on the valve head member 38 over the annular area S, and when such pressure is increased sufliciently, it will overcome the shear strength of the screw or screws 38, 34 holding the spider 29 to the housing 24, and the tie rod 32 to the retainer member 28. Upon such screws being disrupted, the tie rod 32 is released, which then frees the ball valve member 18. At the same time, the valve head member 38 and the retainer member 28 which it engages are then shifted as a unit in a downward direction until the lower portion of the spider 29 engages the housing stop shoulder 35, as disclosed in Fig. 3. When in this position, the cylindrical sealing surface 41 of the valve member 38 is disposed a substantial distance below its companion cylindrical seat 37, and fluid can now flow freely in a downward direction around the ball valve member 18, through the spider 29 and around the valve head 38, exiting from the lower end of the shoe A. Of course, the lower portion 16a of the central passage 16 has a much greater internal diameter than the peripheral sealing surface 41 of the valve head, to allow such fluid passage to take place. If downward pumping of fluid is now stopped, and if any fluid tends to flow in a reverse direction into the well casing, such tendency is forestalled, since the ball valve member 18 is now free to move upwardly into engagement with its companion seat 17 and seal ring 19, occupying the general position disclosed in Fig. 3.

Although described in connection with a back pressure valve member 18, the differential valve mechanism can be used without the back pressure valve member at all, in order to maintain the fluid level within the casing B to a lesser elevation than the fluid level externally of the well casing. When the casing has been run to the desired depth in the well bore, the application of pressure to the fluid within the well casing to a suficient extent to overcome the shear strength of the screw or screws 30 will allow the valve member 38 and spider 29 to shift downwardly to the ineffective position disclosed in Fig. 3, whereupon fluids can pass in both directions between the interior and exterior of the casing string.

The valve device 36, 38, 39, etc. illustrated can also be used in such manner as to allow the casing string B to fill internally completely with fluid. This result can be achieved by omitting the seal rings 51, 53, or by making the areas R and S equal to one another. With such an arrangement, the valve 38 will allow the well fluid to fill to the same level as the fluid externally of the well casing, while maintaining the back pressure valve 18 off its seat. However, when the back pressure valve is to be allowed to engage its seat, then internal pressure can be applied to disrupt the shear screws 30, 34 and shift the control device to the lower position illustrated in Fig. 3, in which the spider and retainer 28 is free from the tie rod 32 and the ball 18, the latter then being capable of moving upwardly into engagement with its companion seat 17, to prevent return flow of Well fluid into the casing.

It is to be noted that by the arrangement described, the passage areas through the differential valve device 38 are quite large. As a result, the velocity of fluid flowing through the valve device 38, when in an open position, is relatively low. The passage areas through the spider 29 are also large. In view of the size of the passage areas and the further fact that the cylindrical seat 37 has a comparatively great diameter, there is less erosion on the parts due to the flow of fluid thereby. In addition, there are no abrupt changes in the direction of the flow of fluid upwardly through the device, which also minimizes erosive wear on the parts. The provision of the large passage areas also prevents their plugging by foreign substances that might be present in the well bore fluid. Substances of even substantial size can pass through the large passages 42, 31, and on up into the casing string B; so that there is less danger of the foreign substances jamming the mechanism and preventing its operation. The large size of the parts obviously means that they are strong and sturdy, the entire mechanism being readily manufactured at a comparatively low cost. In addition, it is to be noted that the seal rings 51, 53 are of relatively small diameter. In view of the fact that these seal rings are subjected to substantially atmospheric pressure within the confined cylinder space 50 on one of their sides, they are subjected to a comparatively great pressure differential, tending to deform them within their ring grooves 52, 54 and against their companion cylindrical sealing surfaces 48, 39. However, despite the comparatively great pressure differentials, the areas of engagement of the seal rings against their companion sealing surfaces are relatively small because of the small diameters of the rings. Accordingly, the total friction force between the rings and the companion surfaces are comparatively small, and are easily overcome by the pressures required in the operation of the device.

The inventor claims:

1. In well apparatus: a tubular member having means thereon for securing said member in a conduit string, said member having a fluid passage; back pressure valve means in said tubular member; shiftable holding means engaging said back pressure valve means to prevent closing of said passage by said back pressure valve means; a second valve means surrounding said holding means and movable relative thereto into engagement therewith and coacting with said passage to control flow of fluid through said passage between the exterior and interior of said tubular member; said second valve means having a first fluid pressure actuatable surface subject to the pressure of fluid in the conduit string above said tubular member to urge said second valve means to passage closing position, said second valve means having a second fluid pressure actuatable surface subject to the pressure of fluid externally of the conduit string to urge said second valve means to passage opening position; the area of said first surface being substantially greater than the area of said second surface; said second valve means, upon engagement with said holding means, shifting said holding means to a position which allows said back pressure valve means to move to closed position and which permits said second valve means to be shifted to a position allowing n flow of fluid in said passage from above said second valve means.

2. In well apparatus: a tubular member having means thereon for securing said member in a conduit string, said member having a fluid passage; back pressure valve means in said tubular member; shiftable holding means engaging said back pressure valve means to prevent closing of said passage by said back pressure valve means; a circumferentially continuous valve seat in said tubular member; a valve member surrounding said holding means and movable relative thereto into engagement therewith; said valve member being movable into and out of engagement with said seat; said valve member having a first fluid pressure actuatable surface subject to the pressure of fluid above said valve member to urge said valve member downwardly into engagement with said seat; said valve member having a second fluid pressure actuatable surface subject to the pressure of fluid below said valve member to urge said valve member upwardly out of engagement from said seat; the area of said first surface being substantially greater than the area of said second surface; said valve member being responsive to the pressure of fluid above said valve member, upon engagement with said holding means, to shift said holding means to a position which allows said back pressure valve means to move to closed position and which permits said valve member to be shifted to a position allowing flow of fluid in said passage in a downward direction.

3. In well apparatus: a tubular member having means thereon for securing said member in a conduit string, said member having a fluid passage; back pressure valve means in said tubular member; shiftable holding means engaging said back pressure valve means to prevent closing of said passage by said back pressure valve means; a circumferentially continuous valve seat in said tubular member; a valve member surrounding said holding means and movable relative thereto into engagement therewith; said valve member being movable into and out of engagement with said seat; said valve member having a I of engagement from said seat; said valve member being responsive to the pressure of fluid above said valve member, upon engagement with said holding means, to shift said holding means to a position which allows said back pressure valve means to move to closed position and which permits said valve member to be shifted to a position allowing flow of fluid in said passage in a downward direction.

4. In well apparatus: a tubular member having means thereon for securing said member in a conduit string, said member having a fluid passage; central means movable in said passage; means releasably retaining said central means in one position within said tubular member; a circumferentially continuous valve seat in said tubular member; a valve member surrounding said central means and movable into and out of engagement with said seat to control flow of fluid in said passage; said valve member having a first fluid pressure actuatable surface subject to the pressure of fluid above said valve member to urge said valve member downwardly into engagement with said seat; said valve member having a second fluid pressure actuatable surface subject to the pressure of fluid below said valve member to urge said valve member upwardly out of engagement from said seat; the area of said first surface being substantially greater than the area of said second surface; said valve member engaging said central means and responsive to the pressure of fluid above said valve member to release said releasable means and enable said central means and said valve member to be shifted to a position allowing downward flow of fluid in said passage.

5. In well apparatus: a tubular member having means thereon for securing said member in a conduit string, said member having a fluid passage; central means movable in said passage; means releasably retaining said cen tral means in said tubular member; a circumferentially continuous valve seat in said tubular member; a valve member surrounding said central means and movable downwardly into engagement with said seat and upwardly out of engagement from said seat to control flow of fluid in said passage; said valve member engaging said central means and responsive to the pressure of fluid above said valve member to release said releasable means and enable said central means and valve member to be shifted to a position allowing downward flow of fluid in said passage.

6. In well apparatus: a tubular member having means thereon for securing said member in a conduit string, said member having a fluid passage; a valve seat in said tubular member; central means movable in said tubular member; means releasably retaining said central means in said tubular member; a valve member surrounding and slidable along said central means into and out of engagement with said valve seat to control flow of fluid in said passage; said valve member having a first fluid pressure actuatable surface subject to the pressure of fluid above said valve member to urge said valve member downwardly into engagement with said seat; said valve member having a second fluid pressure actuatable surface subject to the pressure of fluid below said valve member to urge said valve member upwardly out of engagement from said seat; the area of said first surface being substantially greater than the area of said second surface; said valve member engaging said central means and responsive to the pressure of fluid above said valve member to release said releasable means and enable said central means and valve member to be shifted to a position allowing downward flow of fluid in said passage.

7. In Well apparatus: a tubular member having means thereon for securing said member in a conduit string, said member having a fluid passage; a valve seat in said tubular member; central means movable in said tubular member; means releasably retaining said central means in said tubular member; a valve member surrounding and slidable along said central means downwardly into engagement with said valve seat and upwardly out of engagement from said valve seat to control flow of fluid in said passage; said valve member engaging said central means and seat and responsive to the pressure of fluid above said valve member to release said releasable means and enable said central means and valve member to be shifted to a position allowing downward flow of fluid in said passage.

8. In well apparatus: a tubular member having means thereon for securing said member in a conduit string, said member having a fluid passage; a valve seat in said tubular member; central means movable in said tubular member; means releasably retaining said central means in said tubular member; a valve member surrounding and slidable along said central means into and out of engagement with said valve seat to control flow of fluid in said passage; said valve member having a first fluid pressure actuatable surface subject to the pressure of fluid above said valve member to urge said valve member downwardly into engagement with said seat; said valve member having a second fluid pressure actuatable surface subject to the pressure of fluid below said valve member to urge said valve member upwardly out of engagement from said seat; the area of said first surface being substantially greater than the area of said second surface; said valve member engaging said central means and responsive to the pressure of fluid above said valve member to release said releasable means and enable said central means and valve member to be shifted to a position allowing downward flow of fluid in said passage; and means providing seals between said central means and valve member to form an annular space therebetween into which well fluid cannot enter.

9. In well apparatus: a tubular member having means thereon for securing said member in a conduit string, said member having a fluid passage; a valve seat in said tubular member; central rod means in said tubular member; said rod means having an upper small diameter portion and a lower large diameter portion; means releasably retaining said central rod means in said tubular member; a valve member slidable along said upper and lower portions of said rod means and sealingly engageable therewith to provide a confined space into which Well fluid cannot enter; said valve member being movable downwardly into engagement with said valve seat and upwardly out of engagement from said valve seat; said valve member engaging said central rod means when in engagement with said seat to release said releasable means and to enable said valve member to shift downwardly out of engagement from said seat.

10. In well apparatus: a tubular member having means thereon for securing said member in a conduit string, said member having a fluid passage; a valve seat in said tubular member; central rod means in said tubular member, said rod means having an upper small diameter portion and a lower large diameter portion; means releasably retaining said central rod means in said tubular member; a valve member slidable along said upper and lower portions of said rod means and sealingly engageable therewith to provide a confined space into which well fluid cannot enter; said valve member being movable downwardly into engagement with said valve seat and upwardly out of engagement from said valve seat; said valve member engaging said central rod means when in engagement with said seat to release said releasable means and to enable said valve member to shift downwardly out of engagement from said seat; back pressure valve means in said tubular member; and releasable means interconnecting said back pressure valve means and rod means to prevent closing of said passage by said back pressure valve means.

11. In well apparatus: a tubular member having means thereon for securing said member in a conduit string, said member having a fluid passage; a valve seat in said tubular member; central means in said tubular member;

means releasably retaining said central means in said tubular member; a valve member surrounding and slidable along said central means downwardly into engagement with said valve seat and upwardly out of engagement from said valve seat to control flow of fluid in said passage; said valve member engaging said central means and seat and responsive to the pressure of fluid above said valve member to release said releasable means and en able said central means and valve member to be shifted to a position allowing downward flow of fluid in said passage; back pressure valve means in said tubular member to close said passage against upward flow of fluid; and releasable means interconnecting said back pressure valve means and central means to prevent closing of said passage by said back pressure valve means.

12. In well apparatus: a tubular member having means for securing said member in a conduit string; a housing in said tubular member having a valve seat; central means in said tubular member; means releasably securing said central means to said housing; a valve member surrounding and slidable along said central means into and out of engagement with said valve seat to close and open said seat to flow of fluid therethrough; said valve member having a first fluid pressure actuatable surface subject to the pressure of fluid above said valve member to urge said valve member downwardly into engagement with said seat; said valve member having a second fluid pressure actuatable surface subject to the pressure of fluid below said valve member to urge said valve member upwardly out of engagement from said seat; the area of said first surface being substantially greater than the area of said second surface; said valve member engaging said central means to release said releasable means and enable said valve member to move to a position below and out of engagement with said seat.

13. In well apparatus: a tubular member having means for securing said member in a conduit string; a housing in said tubular member having a valve seat; central means in said tubular member; means releasably securing said central means to said housing; a valve member surrounding and slidable along said central means into and out of engagement with said valve seat to close and open said seat to flow of fluid therethrough; said valve member engaging said central means to release said releasable means and enable said valve member to move to a position below and out of engagement with said seat.

14. In well apparatus: a tubular member having means for securing said member in a conduit string; a housing in said tubular member having a valve seat; central rod means, said rod means having an upper small diameter portion and a lower large diameter portion; means releasably securing said central rod means to said housing; a valve member surrounding and slidable along said upper and lower portions of said central rod means and sealingly engageable therewith to provide a confined space into which well fluid cannot enter, said valve member being movable downwardly into engagement with said seat and upwardly out of engagement from said seat to control flow of fluid through said seat; said valve member having a first fluid pressure actuatable surface subject to the pressure of fluid above said valve member to urge said valve member downwardly into engagement with said seat; said valve member having a second fluid pressure actuatable surface subject to the pressure of fluid below said valve member to urge said valve member upwardly out of engagement from said seat; the area of said first surface being substantially greater than the area of said second surface; said valve member engaging said central rod means to release said releasable means and enable said valve member to move to a position below and out of engagement from said seat.

15. In well apparatus: a tubular member having means for securing said member in a conduit string, said member having a fluid passage; a housing in said tubular member having a valve seat; central means in said tubular member; means releasably securing said central means to said housing; a valve member surrounding and slidable along said central means into and out of engagement with said valve seat to close and open said seat to flow of fluid therethrough; said valve member engaging said central means to release said releasable means and enable said valve member to move to a position below and out of engagement with said seat; back pressure valve means in said tubular member to close said passage against flow of fluid in one direction; and releasable means interconnecting said back pressure valve means and central means to prevent closing of said passage by said back pressure valve means.

16. In well apparatus: a tubular member having means for securing said member in a conduit string; a housing in said tubular member having a valve seat; central rod means, said rod means having an upper small diameter portion and a lower large diameter portion; means releasably securing said central rod means to said housing; a valve member surrounding and slidable along said upper and lower portions of said central rod means and sealingly engageable therewith to provide a confined space into which well fluid cannot enter, said valve member being movable downwardly into engagement with said seat and upwardly out of engagement from said seat to control flow of fluid through said seat; said valve member having a first fluid pressure actuatable surface subject to the pressure of fluid above said valve member to urge said valve member downwardly into engagement with said seat; said valve member having a second fluid pressure actuatable surface subject to the pressure of fluid below said valve member to urge said valve member upwardly out of engagement from said seat; the area of said first surface being substantially greater than the area of said second surface; said valve member engaging said central rod means to release said releasable means and enable said valve member to move to a position below and out of engagement from said seat; back pressure valve means in said tubular member adapted to close to prevent upward flow of fluid through said tubular member and releasable means interconnecting said back pressure valve means and central rod means to prevent closing of said back pressure valve means.

17. In well apparatus: a tubular member having means for securing said member in a conduit string; a housing in said tubular member having a valve seat; a spider in said housing; means releasably securing said spider to said housing; a stem secured to and depending from said spider, said stem having an upper small diameter portion and a lower large diameter portion; a valve member slidable along said upper and lower portions and sealingly engageable therewith to provide a confined space into which well fluid cannot enter; said valve member moving upwardly along said stem out of engagement from said seat and downwardly along said stem into engagement with said seat; said valve member engaging said stem when in engagement with said seat to be acted upon by fluid under pressure above said valve member to release said releasable means and enable said valve member to move to a position below and out of engagement from said seat.

References Cited in the file of this patent UNITED STATES PATENTS 2,300,854 Allen et a1. Nov. 3, 1942. 

